<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <style>
        h1{
            /*red
             #ff0000
             #f00
             rgb(255,0,0)
             rgba(255,0,0,0.5)*/
            color: rgba(255,0,0,0.5);
        }
        div{
            width: 200px;
            height: 200px;
            background-color: red;
            /*设置背景图片*/
            background-image: url("c.jpg");
            /*设置背景图片尺寸*/
            background-size: 100px 100px;
            /*禁止重复*/
            background-repeat: no-repeat;
            /*设置背景图片位置 */
            /*通过横向纵向百分比赋值*/
            /*background-position: 50% 50%;*/
            /*通过像素赋值*/
            background-position: 100px 50px;

        }
    </style>
</head>
<body>
<div></div>
<h1>颜色测试</h1>
</body>
</html>